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Finding the Fourth Proportional to 831.82, 1,247.21 and 311.55

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Solution

The fourth proportional to 831.82, 1,247.21 and 311.55 is: 467.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.82 : 1,247.21 = 311.55 : x
  2. Step 2: Convert to fraction form
    831.82/1,247.21 = 311.55/x
  3. Step 3: Cross multiply
    831.82x = 1,247.21 × 311.55
  4. Step 4: Simplify right side
    831.82x = 388,569.05
  5. Step 5: Solve for x
    x = 388,569.05/831.82
  6. Step 6: Final answer
    x = 467.13

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.